As I think that sidescrollers are part of the shmups family, I thought it'd've been cool to discuss about them to see the tastes of every one of you.

Name your favorite sidescrollers and as I know many games are sidescrolling-related without being real sidescrollers, don't worry about that, name them.

For the ones who think I'm dumb because sidescrollers=shmups, go back learn what a sidescroller is.

My favorite are:

Metal Slug series
Contra
Magician Lord ( I will speak about difficulty )
Castlevania series
...

I know Castlevania is more or less a sidescroller but it doesn't matter. I love it, period.

Concerning the difficulty of Magician Lord, it's barely bearable. Ok, there are 8 worlds of pain in the ass. I managed to reach the 7th. Thanks to between 30 and 40 continues. That means 100-120 lives. For 7 levels.
The 7th already has taken me 20 continues without being completed.

I'M FUCKING FED UP WITH THAT GAME!!

And I just realized the last levels was made of all the guardians to kill in 1 credit. I'm laughing.

I usually don't hate pattern-learning games like Pulstar or viewpoint but this one really blew my rage up.

I like all the ones you listed, but what about Megaman? I grew up playing the 8-bit ones. Then the X series came along as I started to appreciate gaming. It hasn't been so great nowadays, but the old games are still great.

Another great sidescroller was Gunstar Heroes. I played that game with a friend of mine for hours on end. They don't make great co-op games like that anymore.

Strider was a great game as well. That game was so fast and hectic, the sound of the sword cutting was so rewarding, and you could hang off of walls, it was so fun.

I never played Magician Lord though, I might need to check that out...

It's interesting that you'd talk about Megaman because I'm just into it for now on.
I just finished Megaman X4 with X and I'm trying to fight the 8 bosses to Zero but it just seem too hard for me. No matter, it's a pure sidescroller, one that make you remember the best of the genre. Megaman series is one of my favorite series because there are all the ingredients of pure action games.

Megaman 8 is far more easy in the levels but the bosses are a damn hard compared to X4's.
Megaman X will always be my favorite with Megaman, even if Zero's series is tremendously enjoyable.

Concerning Magician Lord, just keep in mind that several people in the neo scene call it the "sidescrolling Pulstar". You've been warned about the insane "pattern-learning" side of the game.

Magician Lord is one of the hardest games I ever played. This game scared me shitless. But it was great!
To my mind, I like the Metal-Slug series, Contra, Rockman, and the former Castlevania...And Mercs, Fixeight, Skyblazer...